Radioreceiver cable connection



y 4- H. c. FORBES ,960,938

RADIORECEIVER- CABLE CONNECTION Filed July 26, 1935 \HH 10 18 V 32 I Q i 4 0", a. 24 36 22 52 26 36 777777 50 48 m 16 20 2 16 76 a g 44 mi 40 BY W ATTORNEYS Patented May 29, 1934 umrso srA'rss PATENT OFFIQE BADIORECEIVER CABLE CONNECTION Application July 26, 1933, Serial No. 682,222

7 Claims.

This invention relates to radio receivers and their installation upon automotive vehicles.

It is an object of the present invention to reduce and substantially eliminate the introduction of extraneous noises entering the radio receiver. This has been accomplished by connecting the shielding of the battery'leads to a point upon the frame or chassis of the radio receiver such that the disturbing influences traversing the shielding means will not be caused to travel through any appreciable portion of the radio chassis or its shielding enclosure.

A further object of the invention is to simplify the installation of radio receivers upon automotive vehicles. This has been accomplished by constructing the shield elements and joining them together and to the support so that the shielding members may be closely bonded together.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawing:

Fig. 1 is illustrative of the present invention in all its phases.

Fig. 2 is a detail construction substantially as 30 illustrated by the line and arrows 2-2 of Fig. 1.

Fig. 3 illustrates a modification of the cable entry and shield bonding means to a radio receiver.

Fig. 4 illustrates still another modification.

In automotive radio installation the battery leads, and other wires or controls entering the chassis of an automobile receiver are known to introduce spark interferences into the receiver. To reduce this interference it has been customary to shield 40 each group of leads or wires or controls in a common braided metal'covering, and to ground the covering at the point Where the cable enters the chassis, the entering point being any convenient point on the radio chassis or its shield.

It has been found that this is an insuflicient precaution, since the interfering currents flowing in the shielded covering of the wires are usually made to flow through the metal parts of the chassis to reach the usual ground, and in so doing 50 induce the interfering noises into receiver circuits so that interference still results. It has also been found that by bringing the shielded cables or wires or controls into the chassis at a point where the chassis is grounded to the metal por- 55 tion of the car uponwhich it is mounted, that the stray currents can be made to flow directly to ground Without passing through any part, or any substantial part of the receiver chassis, and that there is then no resultant interfering currents induced into any of the receiver circuits.

Also the leads or conductors or Wires are shielded all the way to the receiver. It has also been found that it is not sufficient to attach a separate Wire to ground the shields at a point separate from the chassis, as the impedance of such a wire is so high that the high frequency currents causing the interference will not go to ground through such a wire with sufficient ease to prevent the disturbances.

In perfecting the invention and devising a structure to accomplish these results the attendant drawing illustrates the most practical findings. 10 represents a radio chassis upon which various elements of the receiver are mounted and grounded. This chassis and its supported elef ments are enclosed by a box-like shield 12 that may be secured thereto by screws 14 having lock washers 16. Attaching flanges in the form of angle irons 18 are secured to the flange or side Wall of the shield box 12 and provide for cap screws 20 by which the receiver may be mounted upon a metal portion 22 of an automotive vehicle thereby forming a ground connection. Since the circuits of the receiver are grounded to the chassis 10 and the chassis is secured to the shield 12 by some metallic connection equivalent to that described, and since the shield 12 has its ground to a metal portion of the vehicle 22 through the angle irons 18, the elements mounted upon the chassis 10 are directly grounded upon the vehicle. Provision is made by means of an aperture 24 in a depending flange of the chassis 10 for the entry of a multiconductor cable 26 the wires 28 thereof having appropriate connection with the elements mounted upon the chassis. The multi-conductor cable 26 usually has its bunch of wires 28 surrounded by insulated materials such as rubber 30 or the like, in turn enclosed by a fabric sheet 31 that is eventually surrounded and shielded by a woven wire or a braided element 32. In the form illustrated in Figs. 1 and 2, the shielding element 32 also passes through the aperture 24 of the chassis flange and is bonded thereto as by means of solder or the like 34 indicated in Fig. 2.

To make for ready access to the parts of the construction and for desirable separation of the elements during service, both the lower edge of the shield box 12 and the angle iron 18 forming the bracket for its support are notched as at 36 and 38 respectively, so that the shield and bracket may be slipped over the multi-conductor cable. To facilitate the bonding of the shield 32 to the bracket 18, or so as to insure that the shield 32 has a ground connection directly to the metallic part 22 of the vehicle a collar 40 is secured about the end thereof as by soldering indicated at 42, which in turn is metallically secured to the bracket 18 by means of solder applied at 44. The remote ends of the conductors 28 make their several connections with the A, B and C batteries substantially as indicated in Fig. 1, or to another suitable source of potential and that end of the shielding 32 is provided with a ground connection as indicated at 46 which will eventually be the same ground as the element 22 of the automotive vehicle.

When the receiver is thus mounted, the shortest possible ground connections are made between the shield elements and the ground work of the car, and provision is also made for ready access to the receiver for the purpose of servicing. Making for this end the receiver shield 12 is fitted with a removable cover 48 that may be retained in position by means of thumb nuts 50 cooperating with screw studs 52. Should it be necessary to examine or exchange the tubes of the receiver it is but necessary to remove the thumb nuts 50 and thence the cover 48 and do the necessary service work. Should it be necessary to service the receiver more extensively the entire assembly may be removed by running out the screws 20 which will allow removal of the receiver as a whole giving access to the underside of the chassis 10. In the event of inconvenience of access to the parts at fault the screws 14 may then be withdrawn, whereupon the shield casing 12 with its supporting brackets 18 may be slipped from over the chassis 10, especially after breaking the single solder connection at 44.

In Fig. 3, a modification of the cable entry, or rather its metallic connection to the automobile ground is illustrated, in which the shield covering 32 is flared outwardly so as to be disposed between the depending chassis 10 and the side wall of the shield case 12. In this construction, when the screws 14 are driven home, the flared out portion of the shield 32 will be securely clamped as indicated at 54. In this construction, as well as that heretofore described, disturbing influences that are picked up by the shield 32 pass directly to ground without passing through any portion of the receiver chassis and thereby tend to eliminate the disturbing influences. In the third modification illustrated in Fig. 4, further provision is made for anchoring the shield 32 by slightly recessing the contiguous faces of the chassis 10 and the shield 12 substantially as indicated at 56 and 58 respectively. These recesses are only of such magnitude that the flared out portion of the shield 32 will be securely clamped between the chassis 10 and the shield 12 when the screws 14 are driven home.

In the instance of either disclosure the stray currents that may be made to pass through the shielding element 32 upon reaching the receiver will pass directly to the ground 22 without passing through any appreciable portion of the chassis 10. In the disclosure illustrated in Figs. 1 and 2, this passage is through the collar 40, the bonded point 44 and the bracket 18. It may also include the soldered or bonded connection 34 thence across the depending flange of the chassis 10, the shield element 12 and the bracket 18 and to ground. In the forms illustrated in Figs. 3 and 4, the passage is from the expanded portion of the shield element 32 through the adjacent portion of the shield 12 to the bracket 18 and thence to ground.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follows.

What is claimed is as follows:

1. In a radio receiver for automotive installation, the combination comprising, a chassis supporting the receiver and forming a common ground for the elements thereof, a shield for enclosing said chassis and receiver, leads connecting the receiver into a complete radio receiving circuit, at least part of said leads being grouped into a cable, means shielding at least a part of said leads, and means grounding said cable shield at the point of chassis ground so as to avoid interference from extraneous sources.

2. In a radio receiver for automotive installation, the combination comprising, a chasis supporting the receiver and forming a common ground for the elements thereof, a shield for enclosing said chassis and receiver, leads connecting the receiver into a complete radio receiving circuit, at least part of said leads being grouped into a cable, means shielding at least a part of said leads, and means grounding said cable shield at a point substantially coincident with the ground of said shield so as to avoid interference in the radio receiver from extraneous sources.

3. In a radio receiver for automotive installation, the combination comprising, a chassis supporting the receiver and forming a common ground for the elements thereof, a shield for enclosing said chassis and receiver, leads connecting the receiver into a complete radio receiving circuit, at least part of said leads being grouped into a cable, means shielding the leads of said cable, and means grounding said cable shield at the point of chassis ground so as to avoid inter ference in the radio receiver from extraneous sources.

4. In a radio receiver for automotive installation, the combination comprising, a chassis supporting the receiver and forming a common ground for the elements thereof, a shield for enclosing said chassis and receiver, leads connecting the receiver into a complete radio receiving circuit, at least part of said leads being grouped into a cable, common means shielding the leads of said cable, and means grounding said cable shield at a point substantially coincident with the ground of said chassis so as to avoid interference of the radio receiver from extraneous noises.

5. In a radio receiver for automotive installation, the combination comprising, a chassis supporting the receiver and having a common ground on the automotive structure for the elements of said receiver, a shield for enclosing said chassis and receiver, leads connecting the receiver into a complete radio receiving circuit, at least parts of said leads being grouped into a cable, means shielding at least a part of said leads, and means grounding said cable shield at the point of chassis ground so as to avoid interference in the radio receiver from extraneous sources.

6. In a radio receiver for automotive installation, the combination comprising, a chassis supporting the receiver and having a common ground on the automotive structure for the elements of said receiver, a shield for enclosing said chassis and receiver, leads connecting the receiver into a complete radio receiving circuit, at least nation comprising, means shielding the radio receiver and grounding the chassis thereof upon the metal structure of the vehicle, battery leads connected into the receiver chassis, shielding means for the battery leads, and means grounding the lead shielding means so as to tend to prevent the passage of any disturbing currents to any part of the receiver chassis.

HENRY C. FORBES. 

